Putin redoubled his efforts to encourage businessmen to "deoffshore" their assets on Thursday in his annual end-of-year news conference, as the country's economy heads for recession, dragged down by a slump in oil prices and Western sanctions.

"This step is related to the announcement by President Vladimir Putin of pursuing the deoffshorization of the Russian economy and the introduction to the tax code of clauses related to taxation of profits of ... foreign companies," USM Holdings said in a statement.

Usmanov is the biggest shareholder at USM Holdings with a 48 percent stake, while his long-time partners Vladimir Skoch and Farhad Moshiri own 30 percent and 10 percent respectively.